Writing instrument



FIG. 1 is a rear elevational view of an embodiment of the writing instrument showing our new design;

FIG. 2 is a first side elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG 4 is a second side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a writing instrument, as shown. 